Martin I. Reiman

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T he most common model to support workforce management of telephone call centers is the M/M/N/B model, in particular its special cases M/M/N (Erlang C, which models out busy signals) and M/M/N/N (Erlang B, disallowing waiting). All of these models lack a central prevalent feature, namely, that impatient customers might decide to leave (abandon) before their(More)
We develop a framework for asymptotic optimization of a queueing system. The motivation is the staffing problem of large call centers, which we have modeled as M/M/N queues with N , the number of agents, being large. Within our framework, we determine the asymptotically optimal staffing level N ∗ that trades off agents’ costs with service quality: the(More)
Avi Mandelbaum , William A. Massey b and Martin I. Reiman c Davidson Faculty of Industrial Engineering and Management, Technion Institute, Haifa 32000, Israel E-mail: b Bell Laboratories, Lucent Technologies, Office 2C-320, Murray Hill, NJ 07974, USA E-mail: c Bell Laboratories, Lucent Technologies, Office(More)
We consider the problem of scheduling a queueing system in which many statistically identical servers cater to several classes of impatient customers. Service times and impatience clocks are exponential while arrival processes are renewal. Our cost is an expected cumulative discounted function, linear or nonlinear, of appropriately normalized performance(More)
We analyze two scheduling problems for a queueing system with a single server and two customer classes. Each class has its own renewal arrival process, general service time distribution, and holding cost rate. In the first problem, a setup cost is incurred when the server switches from one class to the other, and the objective is to minimize the long-run(More)
This paper studies the classical polling model under the exhaustive-service assumption; such models continue to be very useful in performance studies of computer/communication systems. The analysis here extends earlier work of the authors to the general case of nonzero switchover times. It shows that, under the standard heavy-traffic scaling, the total(More)